shopping centre vs sales outlet

shopping centre and sales outlet both are nouns.

Word	Noun	Adjective	Verb	Adverb
shopping centre	Yes	No	No	No
sales outlet	Yes	No	No	No

As nouns, sales outlet is a hypernym of shopping centre; that is, sales outlet is a word with a broader meaning than shopping centre:

shopping centre: mercantile establishment consisting of a carefully landscaped complex of shops representing leading merchandisers; usually includes restaurants and a convenient parking area; a modern version of the traditional marketplace
sales outlet: a place of business for retailing goods

Other hypernyms of shopping centre include mercantile establishment, outlet, retail store.

shopping centre (noun)	sales outlet (noun)
mercantile establishment consisting of a carefully landscaped complex of shops representing leading merchandisers; usually includes restaurants and a convenient parking area; a modern version of the traditional marketplace	a place of business for retailing goods